Designing on scaled absorbing materials at THz band using Ni@mica composite

The scaled measurement on the target model coated with the frequency dispersion absorber with a large-scaled factor was still an unsolved problem. In this work, the scaled absorbing material with the scale factor 100 was designed at Terahertz (THz) band using the hybrid Ni@mica particle. The designing method on the scaled absorber was composed with the particle distribution designing, permittivity interpolation method, and multilayer structure optimization. The complex permittivity and permeability were measured first on the THz time-domain spectroscopy (TDS) measurement system in frequency 0.8–1.8 THz as the Ni@mica particle-filling ratio of the absorber was 30%, and then, the reflection loss could be calculated. As the different holes were set in the absorbing squared body element, the transmission ratio and the reflection ratio of the absorbing composite were simulated in the computer simulation technology (CST) software, and the effective permittivity and permeability could be calculated. Then, the permittivity data base with different holes was built by the Lagrange interpolation method. Finally, the scaled absorber materials could be optimized for the magnetic coating plate at 1 THz and 0.8 THz, and the designed scaled absorber included two layers: the bottom layer thickness was 0.12 mm with volume content 30% and the upper layer thickness was 0.17 mm with volume content 27%. The calculation result showed that the radar cross section (RCS) deviation between the two similar models was − 40.02dB@8GHz and − 40.21dB@10GHz, which were very close to the theoretical value − 40 dB. It indicated that the Ni@mica was one of the effective candidates to construct the scaled absorbing material.